A method for detecting the presence of a microorganism in a fluid sample is disclosed. The method includes providing a fluid specimen within a specimen collection container having a sidewall defining an interior therein. The interior includes a mechanical separator adapted for separating the fluid sample into first and second phases within the specimen collection container and a sensing element capable of detecting the presence of a microorganism disposed therein. The method includes subjecting the specimen collection container to applied rotational force to isolate a concentrated microorganism region. The method also includes detecting by a sensing element the presence or absence of a microorganism within the concentrated microorganism region.